1. Field of the Invention:
The present invention relates to a needle thread drawing device of a sewing machine having a thread end holding unit for applying tension to the needle thread.
2. Description of the Prior Art:
A prior art machine is provided with a thread end holding unit which incorporates a thread cutting device for cutting off a needle thread and a bobbin thread under the processed cloth upon completion of subjecting a piece of processed cloth to a series of stitching operations in the sewing machine. This unit also draws and holds the thread end of the cut off needle thread at the upper side thereof. This thread end holding unit has the function of preventing the thread end of the needle thread from being entangled to form like a bird's nest at the rear side of the processed cloth at the time of starting the stitching operation for the succeeding processed cloth.
Another prior art thread end holding unit is disclosed in Japanese Utility Model Publication No. 61-8863. This thread end holding unit comprises a needle thread gripping puller provided at the side of an arm of the sewing machine. This puller is driven to take a catch position or a return position and has a hook portion for passing the needle thread extending downward from the needle toward the processed cloth, at the time of forward movement, to take the catch position and for catching the needle thread at the time of taking the return position. Two holding members are secured to the side of the arm of the sewing machine for accommodating telescopically the needle thread gripping puller and for pressing and holding the needle thread contacting the needle thread gripping puller at the tip end thereof when caught by the hook portion at the time when the needle thread gripping puller takes the return position.
However, in the prior art thread end holding unit, inasmuch as the needle thread can be caught by the hook portion of the needle thread gripping puller, and the needle thread gripping puller pushes the needle thread extending perpendicularly from the needle toward the processed cloth to take its ultimate position at the time when the needle thread gripping puller takes the forward movement so as to be positioned in the catch position, a loose portion of the flexible needle thread would be formed. As a result, when the needle gripping puller is moved from the thread catch position to the return position, a condition can occur wherein the hook portion of the needle thread passing the same route as the forward movement does not catch the needle thread. At this time, the thread end holding unit does not perform properly and the quality of the processed cloth deteriorates.